Brake mechanism



Wnlented Mar. 1l, 1941 UNITED l STATES 2,234,897 BRAKE MEcHANIsM WilfredA. Eaton, Pittsburgh, Pai, assigner to Bendix-Westinghouse AutomotiveAir Brake Company, Pittsburgh, Pa., a. corporation of DelawareApplication November l., llldd, Sendai No, dtdl l2 Claims.

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pressure .to and from fluid motors of the type used for actuatingvehicle brakes. Such systems have, however, in many cases, required theuse oi special and comparatively complicated braise valve structures foreffecting the necessary 'coordinated control of theelectrically-operable valves.

lt is accordingly an object of the present lnvention to overcome thesedifficulties and to provide, in a system oi the above described type,controllins,r means for the magnet valves which may be readily adaptedfor Ause in connection with uralte valves of the type already in commonuse.

lEtralte valves of the type above referred to are frequently providedwith a pair of chambers connected by a restricted passage, which acts tocreate a varying pressure differential between the chambers duringoperation of the valve, and another object of the invention is theutilization ci' the pressure differential thus created lor controllingthe operation of the magnet valves.

Yet another object is to provide, in connection with brake val-ves ofthe above type, mechanisin for controlling energization of the magnetvalves, so constituted as to prevent enerslzatlon of the magnet valvesand consequent loss ol electrical energy when the brake valve is ineither released or lapped position.

d further object of -the `invention is .the pro- W vision, in a controlsystem ofthe above character, of mechanism so constructed as to permitoperation and control of the brakes by the rbrake valve alone lin theevent of failure of the supply of electrical energy for operating themagnet d valves.

These and other objects of the invention will be more readily apparentwhen taken in connection with the accompanying drawing,A wherein oneform of the invention isillustrated. It is to to rhe expresslyunderstood, however, that the draw- In lthe drawing,v the single view isa. diagramlci, vtaitl matic representation, partially in section, of aduid inotor control system constructed in accordance with the principlesol the present invention.

heierrdna t-o the drawing, the invention is d illustrated as including aself-lapping brake valve t, which may be ont the general type disclosedin the patent to William il. Andres and Roy S. Sanford No. 2,133,275,dated @ctober ld, i938, having a casina t provided with an outletchamber 1@- t connected to a duid motor "l by means of conduit t, and aninlet chamber t connected .to a duid pressure reservoir ld by n'ieansoi' a conduit ll. lhe outlet chamber is separated from. theinlet chamberby a partition it provided on its lower side with an intatte valve seatld, and corninunication between the two chambers is norreallyinterrupted by means oi an intake valve lt held aeainst seat it by aspring l li interposed between the upper sid@ oi partition lt and an f2@exhaust valve ida positioned in the outlet cham bei' and rigidlyconnected to the intake valve loy a valve stern it. d valve-operatingelement ll,

normally spaced from exhaust valve its, is secured as shown to adeitilole diaphragm member 25 it carried bythe casina and dividing theupper ,portion thereot into diaphragm and exhaust chambers it and itrespectively, the former chamber beine connected with the outlet chambert .by a choked passage tl and the diaphragm chamber beine connected toatmosphere by means'l of anexhaust pont it. in exhaust valve seat t-l isformed at the lower end of valve-operating elementl ll, and a bore itformed in element ll concentric with the seat normally serves to connectoutlet chamber t with exhaust chamber 2d through a port 2t leading fromthe bore 24 to the exhaust chamber. The intake and exhaust valvw arereadily operated'by means of a foot pedal 26 pivotally mounted on aportionoi' the 40 casing 5 and connected with the valve-operatingelement il through a" graduating spring 21 interposed between a plunger23 actuated by the pedal and a spring seat 29 carried by the element l1.

It will be understood by those familiar with the type of ybrake valveabove described that, when the brake pedal -2t is depressed apredetermined amount and held in such position, the air pressure inchamber I9 acting on the lower side of diaphragm Il will eventuallybalance .the spring force exerted by the graduating spring 21, at

which .fpoint the diaphragm will move 'the valveoperating element l1 toa position at which both the intake and exhaust valves -are-in closedposition, withfthe pressure in the outlet chamber of the brake valve andin the vfluid motor elastantially proportional to the degree of movementof the brake valve pedal.. As more thoroughly explained in the aboveAreferred to patent, the choke 2fl between the outlet chamber 6 and thediaphragm chamber I9 serves to delay the iiow o f iiuid pressure fromchamber- 6 to chamber i9.'

the result being that, on a sudden application oi the brake valve, thepressure in chamber I9 builds up at a much slower rate :than Atherpressure in chamber 6, while, on release-of the brake valve pedal, itwill be obvious that the reverse action takes place. Y

The pressure differential just referred to as existing between chambers6 and i9 is taken advantage of in .the present invention to operate acontrol switch, which in the illustrated em-v bodiment is shown ascomprising a switch mechanism Sil, having a casing 3l, divided in-tochambers 32 and 33 by diaphragm 64 carried by the casing 3i. The upperportion oi' the casingeis provided with a pair of contactA members-35and 36 insulated from the "casing, such members being adapted lto beconnected when contacted by the switch member 3'! carried by thediaphragm. The lower portion of the casing is providedwith like members38 and 39, which are adapted to be connected by the switch member Q0,carried by Ithe diaphragm. In order that the diaphragm m-ay beresponsive to the pressures in chambers and i 9, chamber 32 is connectedto chamber i9 as by means of a conduit dii', while chamber 33 isconnected to the outlet conduit 8 or directly to the chamber 6 as bymeans of a conduit lli. it will be readily apparent from the foregoingdescription that, on a sudden application of the brake pedal, thepressure in chamber t will be greater than that in chamber i9, asheretofore described, with the result that the iiuid pressure inlchamber 33 will force the diaphragm 34 upwardly causing the contactmemlber 31 to complete the circuit between the contacts 35 and 35, while.a sudden release of the brake pedal will result in the pressure inchamber i 9 being greater than .that in chamber 6, whereupon the dia;phragm 34 will be forced downwardly so as to cause the member 40 tocomplete the circuit between the contact members 35 and 39.

In order that the supply of fluid pressure may be delivered to andreleased from the uld motor 'i as rapidly as possible, there is providedand illustrated in the present invention a double magnet valve 42,having an outlet chamber d3 connected to the fluid motor conduit 3 bymeans o f conduit 44, and to the supply reservoir i0 by means of conduit45, communication between the outlet chamber 43 and conduit i4 beingnormally interrupted by means of valve 46 held against the outlet ofchamber 43 by means of a spring 41. A casing 43 of suitable .magneticmaterial encloses a magnet'coil 49 and,

in connection with a center pole piece 5I, acts to move the valve toopen positionwhenever the coil is energized. The right hand portion of.the magnet valve .is provided with an exhaust chamber 5|, having aconduit 52'1eadingto atmosphere, together with a conduit 53 connected tothe conduit 44 leading to-.the tluid motor. An exhaust valve 5Iaordinarily closes the outlet to conduitl 52, and is held in `thisposition by means ci' an exhaust valve spring 54, and it will be readilyseen that energization of magnet coil 55, carried by4 casing 43, willcause the lpole piece 56 to move valve 5Ia upwardly so esto convmotor4'l and atmosphere through conduit 8, connect chamber 5i with theatmosphere, thus exhausting iiuid from the iiuid pressure motor.

Since iiuld motors for operating brake mechanism are ordinarily locatedat a point remote from the regular brake control valve, a long conduit'is necessary to connect the brake valve with .the motor. It will benoted that, by the present invention, the use of an ordinary brake valvetogether with an auxiliary electrically-,operated valve provides for thecontrol of iiuid pressure to the motor, not only through the regularbrake valve, but also through the magnet valve which is located at apoint adjacent to the fluid motor i.

in order thatthe magnet valve may operate 15 to satisfactorily carry outthe function above described, two of the terminals of magnet coils i9and 53 are connectedl together by a common connector 61, while the otherterminal of the coil i9 is connected'tc the switch contact 35 by 20means of a connection 56. The contacts 36 and 39 of the switch 30 areconnected together by means of connection 59, and the latter connectionls connected to the magnet terminal wire bll by .means of connection 6D,battery 6l and Q5 connection d2, it being thus apparent that, on upwardmovement of the diaphragm 34, the member 8l will serve to complete thecircuit from the battery iii to the magnet coll 9 by means of theconnections above described. 3 whereupon the valve i6 will be movedupwardly and permit the now of fluid pressure from reservoir i@ toiluidmotor ll through conduit 45, mag'- net valve Aoutlet chamber 43, conduiti4 and conduit El. In like manner, the right hand terminal 3 of magnetcoil 55 is 'connected to the Contact 38 of switch 3@ b'y means of aconnection 63, this connection being such that, on downward movement ofdiaphragm S4, electrical energy from. the battery iii will be conductedto magnet coil through connection 62, connection 51, and back to thebattery through connection 63, contact 3S, contact 4U, contact 39, aportion of connection 59 and connection G50.

' From the foregoing description, it will be understood that, onLdownward movement of the brake pedal 26 to effect a brakeV application,the excess air pressure in outlet chamber 6 of the brake valve will movethe switch diaphragm 34 upwardly to connect contacts 35 and 36 andenerglze the magnet coil 49, which will in turn open the valve 46 andpermit fluid under pressure to flow directly from reservoir iU'tc' theiiuid motor' through conduit 45, chamber 43, conduit 44 and conduit 8,while releaseof the brake pedal to effect release of fluid -pressurefrom the motor 1 to conduit 8 will cause the excess pressure in chamberi9 of the brake valve to depress diaphragm 34 and cause contact member46 to establish the circuit between contacts` 38 and 39, whereupon themagnet coil 55 will magnetize the pole piece 56 which in/turn willattract the valve 5Ia, opening the valve and establishing a connection`between the fluid 55 duit 44.*conduit 53, chamber 5l and conduit 52.

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correspond very closely to the operations of the corresponding valves inthe brake valve, while lib bill

operation of the manually-operated brake valve such as to cause abalance of pressure within the bralre valve in chambers 6 and I9 'willcause a corresponding balancing action of diaphragm 34, with the resultthat, when the brake valve comes to lap position, the diaphragm 34 ofthe switch mechansm will also be in lap position, and both' valves cithe magnet valve will be closed. It is also to be noted that, with thearrangement shown, no current is consumed from the battery tl duringperiods in which the brake valve is in released position or is inapplied position `with the pressures balanced.

Although the invention has been illustrated and described herein withconsiderable particularity, it is to be'understood that the same is notlimited to the form shown but may receive a variety of mechanicalexpressions, as,will readily appear to those skilled in the art..Reference will, therefore, be had to the appendedl claims for adefinition of the limits of the invention.' What is claimed is:

l. l'n combination with a source of fluid pressure and a fluid motor, ofelectrically-operable valve means for controlling the now oi` fluidpressure between said source and motoran Voperator-controlled valvularmechanism ihr: vcon- 'trolling the now of fluid pressure betweefif'the:`

outlet chamber having a connection with the fluid litt ltd

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motor, a diaphragm chamber, and a restricted connection between saidoutlet chamber and diaphragm chamber for effecting a fluid-pressuredifferential between said chambers during changes or pressure in saidoutlet chamber, and means including a member responsive to thepressuresin said chambers for controlling the operation oi saidelectrically-operable valve means.

2. A huid motor control system having a fluid motor and a source offluid pressure, and means lor controlling the flow of fluid pressurebetween the sourceand the motor including a self-lapping valve mechanismof the type having an outlet chamber connected with the motor, a valvefor controlling the flow of fluid pressure between the source and theoutlet chamber, a second chamber having a restricted connection with theoutlet chamber, and a pressure-responsive member associatedwith saidsecond chamber and subjected to the pressure therein for controlling theoperation of the valve, auxiliary valve means for controlling the now ofIiuid pressure between the source and the motor, and means including asecond pressure-responsive member subjected to the pressures in both ofsaid chambers for controlling the operation of said auxiliary 'valve lidmeans.

3.v A fluid motor control system having a fluid motor and a source offluid pressure', and vmeans tor controlling the flow of fluid pressurebetween said source' and motor including a self-lapping valve mechanismof the type having an outlet chamber connected with the motor, a valvefor vcontrolling the flow of fluid pressure between the the motor, asecond connection between said second chamber and outlet chamber, andmeans including a second pressure-responsive member associated with saidsecond connection and subjected to the pressures in both of saidchambers for controlling the operation of the auxiliary valve means.

4. A iluid motor control system having a fluid motor and a source offluid pressure, and. means for controlling the flow of fluid pressurebetween said source and motor including a self-lapping valve mechanismof the type having an outlet chamber connected with the motor, intakeand exhaust valves for controlling the ilow oi huid pressure throughsaid outlet chamber, a second chamber having a restricted connectionwith the outlet chamber, and a pressure-responsive member associatedwith the outlet chamber and subjected to the pressure therein forcontrolling the operation of the valves, auxiliary valve means includingan outlet chamber connected with the motor and valves for controllingthe flow of rluid pressure through said chamber, and means lncludingpressure-responsive means subjected to the pressures in the first namedoutlet chamber and in said second chamber for controlling the operationof said auxiliary valve means.

5. A uid motor control system having a fluid motor and a source or fluidpressure, and means for controlling the rlowoi fluid pressure betweensaid source and motor including a self-lapping valve mechanism ci thetype having an outlet chamber connected with the motor, valves forcontrolling the flow oi fluid pressure through said chamber, a secondchamber having a restricted connection with said outlet chamber, andpressure-responsive means associated with said sec ond chamber andsubjected to the pressure there-v in for controlling the operation ofthe valves, electrically-operable auxiliary valve means for con-Itrolling the flow of huid pressure between the source and motor, andmeans for controlling the energization ci saidelectrically-operablelauxil;

, a pair of chambers and means for subjecting said chambers todifferential pressures during fluid pressure flow controlling operationof the valve and for subjecting the chambers to the pressure in themotor when the valve is lapped, of means controlled by the pressures inboth of said chambersr for controlling the operation of said auxiliaryvalve.

7. A fluid motor'control system having a fluid motor 'and a source offluid pressure, and means for supplying and exhausting fluid pressure toand from said motor including a self-lapping valve mechanism of the typehaving an outlet chamber connected to the motor, intake and exhaustvalves for controlling the flow of fluid pressure through said outletchamber, a second chamber having a restricted connection with saidoutlet chamber, and a pressure-responsive member associated with theoutlet chamber and subjected to the pressure therein for controlling theoperation of the valves, electrically-operable valve mechanism includingan outlet chamber oonnected with the motor and intake and exhaust valvesfor respectively establishing communication between the source of uidpressure and the last named outlet chamber and for exhausting iluidpressure from the outlet chamber,andmeans controlled by. the pressure inthe outlet chamber of the self-lapping valve mechanism for controllingoperation of the intake valve of said electrically-operable valvemechanism and controlled by the pressure in the second chamber of theselilapping valve mechanismior controlling the operation of the exhaustvalve o the electricallyoperable valve mechanism.

8. A fluid motor control system having -a iuid motor and a source offluid pressure, and means lfor supplying and exhausting fluid pressureto and from said rnotor including a self-lapping valve mechanism of thetype having an outlet chamber connected with the motor, an intake valvefor establishing communication between said outlet chamber and source, avalve operable for exhausting fluid pressure from said chamber, a secondchamber having a restricted connection with said outlet chamber, andmeans including a` pressure-responsive member associated with saidsecond chamber and subjected to the pressure therein for operating and4controlling the operation of said valves, auxiliary valve means havingan outlet chamber connected with the motor and including individuallyelectrically-operable intaire and exhaust valves for respectivelyestablishing communication between said source and outlet chamber andfor exhausting fluid pressure from said chamber, a switch forcontrolling operation of said intake valve, 'a second switch forcontrolling the operation of said exhaust valve. and means responsive toan excess of pressure in the outlet chamber nof vthe self-lapping valvemechanism for closin'gthe first named switch and responsive to an excessof pressure in the second chamber o! said valve mechanism for closingthe second switch.

9. A fluid motor control system-having a uid motor and a source of fluidpressure, and means for supplying and exhausting :duid pressure to andfrom said motor includinga self-lapping valve having an outlet `chamberconnected to the motor and `a second chamber connected to the outletchamber by a restricted passage, intake and exhaust valves forrespectively establishing communication between said source and outlet`chamber and exhausting iluid from said outlet chamber, and meansincluding a pressure-responsive member for controlling the operation ofsaid valves, auxiliary yvalve means having an outlet chamber connectedwith the motor and intake and exhaust valves for respectivelyestablishing communication between said last named chamber and sourceand exhausting iluid pressure from said chamber, and means forindividuallycontrolllng and operating the intake and exhaust valves ofsaid auxiliary valve including means responsive to the pressure in theoutlet chamber of the self-lapping valve for controlling operation ofthe last-named intake valve and responsive to the pressure in the secondchamber of the self-lapping valve for controlling operation of said lastnamed exhaust valve.

10. A i'luid braking system having a fluid-operated motor, a source offluid pressure, an elecl0 trically-operated application valve forconnecting said source and motor, an electrically-operated release valvefor connecting said motor to atmosphere, and means for alternatelyenergizing said valves comprising a pressure-responsive switch 15movable in opposite directions, self-lapping valve means for controllingthe operation of said switch and having a chamber adapted to beconnected with said source and a second chamber in constant restrictedcommunication with said first 20 chamber, and separate connectionsbetween said rst and second chambers and said pressure responsive switchfor rendering the self-lapping valve controlling action thereoneilec'tive.

il. A iluid braking system having a iluid-oper- 25 l ated motor, asource of uidpressure, an electrically-operated application valve forconnecting said source and motor, an electrically-operated release valvefor connecting said motor to atmosphere, and means for alternatelyenergizing 30' said valves l comprising a pressure-responsive switchmovable in one direction to energize said application valve and movablein the opposite direction to energize said release valve, and meansincluding a self-lapping .brake valve for control- 35 ling the operationof said switch, said brake valve having 'an outlet chamber connectedwith said motor and 'adapted to be connected with said source, a secondchamber in restricted conmunication with said .first chamber, and meanscon- `40 self-lapping brake valve.

1 l2. A iuid motor control system having a uid motor and a source offluid pressure, means for controlling the supply of fluid' pressure tosaid motor including a valve for connecting said source and motor,auxiliary electrically operable valve means for connecting said sourceand motor. means including a switch for controlling the energization ofsaid last named valve means, said switch including a casing having apair of chambers and a pressure responsive member subjected to thepressures in both of said chambers, and

means for supplying differential pressures to said chambers including adirect connection between the motor and one of the chambers and a rela"tively restricted connection between the motor 60 and said otherchamber.

WILFRED A. EATON. r

